1. Field of the Invention
This invention relates to a long range artillery shell.
2. Discussion of the Prior Art
There is a constant military requirement to extend the range of artillery shells with minimum effect on payload and delivery errors.
In practice this suggests maintaining the general physical shape of current conventional shells. Moreover, it is desirable for the external dimensions and mass of an extended range shell to conform closely to the external dimensions and mass of existing shells, in order that it be launchable from existing ordnance without exceeding the maximum acceptable breech pressure. There are great advantages for a long range shell if these requirements can be achieved.
It is possible to extend the range of shells by incorporating a rocket motor to provide thrust after launch. The trade-off for the incorporation of a rocket motor is the loss of payload corresponding to the volume occupied by the rocket motor. As an example, rocket assistance can extend the range of a 155 mm artillery shell by approximately 23% whilst sacrificing approximately 64% of its payload.
It is possible to extend the range of shells by means of base bleed. Base bleed increases range by reducing the base drag of the shell by increasing its base pressure. This is achieved by the combustion of a propellant which exhausts its gases into the base region of the shell. The advantage of base bleed as a range enhancer is the much smaller volume requirements of the motor for a given range increase. As an example, base bleed can extend the range of a 155 mm artillery shell by approximately 23% whilst sacrificing approximately 18% of its payload.
Neither rocket assistance nor base bleed are capable of achieving the desired ranges with a reasonable payload. The problem is how to increase range further whilst maintaining the overall dimensional constraints of existing shells and providing for a reasonable payload.